High Quality h264 vs Prores

Hi all,
I need to send an onlined 2 hour HD film overseas (100GB). Shipping is not an option due to time constraints. I am considering encoding it in high quality h264, uploading and having them convert back to Prores on their end for tape out.

Is this a huge "NO NO" in postproduction land, or is the quality loss negligible with super high quality h264?

I've delivered high quality H.264 as show masters for a couple networks. But then they aired the H.264's directly. I'd test to see what two conversions will look like...but that workflow sounds reasonable...ish.

An SD ProRes LT file would be much smaller and could be used directly to output to tape in SD at the Russian end. Next step down would be XDcam also in SD as it can also be used without reconverting back to ProRes at the other end.